1. Field of the Invention
The present invention relates to a measurement apparatus, an exposure apparatus, and a device fabrication method.
2. Description of the Related Art
An exposure apparatus is employed to fabricate semiconductor devices using photolithography. The exposure apparatus projects and transfers a pattern formed on a reticle (mask) onto a substrate such as a wafer by a projection optical system. In recent years, as semiconductor devices are further miniaturized, the exposure apparatus must precisely transfer the pattern of a reticle onto a wafer at a predetermined magnification. Hence, the imaging performance of the projection optical system must be measured with high accuracy. To meet this requirement, U.S. Pat. No. 6,816,247, for example, proposes a technique for measuring the distortion of the projection optical system.
However, since the projection optical system to be measured has various imaging performances such as a curvature of field, distortion, and wavefront aberrations. It has recently been demanded to develop a new technique which can measure, among others, the curvature of field of the projection optical system.